Rishi Sunak will call a general election for 4 July, Sky News understands.
The prime minister will make a statement in Downing Street at 5pm, when he is expected to name the date of the vote.
The surprise move comes as the Tories trail Labour by 20 points in the polls, and face being ousted by the Opposition after 14 years in government.
Mr Sunak may be gambling on the fact that the improving economic outlook will give him a fighting chance of winning.
Earlier today, the Tory leader declared inflation was "back to normal" in a "major milestone" for the country, following official figures showing inflation slowed to 2.3% in April
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Would you trust a political leader who calls a surprise election when their party is significantly behind in polls?
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Do you believe that a single economic achievement, like reducing inflation, should be a decisive factor in a general election?